Andy Murray will hope he can at last trust his body when he plays his second-round match against Matthias Bachinger at the US Open today.
The Scot arrived in New York in a positive frame of mind and declared himself in his best shape since winning Wimbledon last year following a training camp in Miami.
After 18 months of back problems followed by surgery and then the lengthy process of getting back to full fitness, it has been a long time since Murray felt at the peak of health on the court.
He thought that would be the case in his first-round match against Robin Haase on Monday, only for cramp to come on at the start of the third set.
Murray dismissed nerves as a cause and has instead been focusing on what he ate and drank in the build-up to the match.
But it would not be surprising if Murray had been tense considering he has been unable to get back to his best form since back surgery almost a year ago.
Roger Federer endured his own back problems last season, although did not need surgery, and found his mind took longer to heal than his body.
Murray said: "I think if you have a physical issue that's hampering you, it's very easy for that to take over your thinking when you're on the court.
"It's frustrating to not be able to do the things that you want your body to do and that distracts you from what you should be doing on the court, which is trying to beat your opponent, not how you have to move to your backhand side or your forehand side or whatever the issue is."
Meanwhile, fourth seed Agnieszka Radwanska became the first major casualty of the US Open when she was dumped out in the second round by Peng Shuai. Radwanska dropped just one game in a rapid first-round win over Sharon Fichman but world number 39 Peng was a deserved 6-3 6-4 winner.
The Chinese player looked like she might have missed her chance when two match points went begging, one on the Radwanska serve at 5-3 and the second on her own delivery.
Radwanska had a chance to make it 5-5 but missed it and Peng took her third match point with a backhand winner onto the line.
It was deja vu for Radwanska, who suffered her only previous loss to Peng in the second round at Flushing Meadows four years ago.